ED73.9002: Processing Effects on the functional

components of food

Acrylamide: Thermal Process induced Toxicant

By-Yakindra Prasad Timilsena

(111332)Jyotsna Shrestha Khanal

(111328)1

• Introduction • Mechanisms of formation• Toxicology• Amounts in different food sources• Regulations & allowable limits• Methods of Determination• Preventive measures• Conclusion

Presentation Outline

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Less tasty side to these culinary delights:

Thermally induced harmful chemicals (Carcinogens)

3

• Synthesized for the first time in 1949• Unsaturated & highly reactive

amide• White odorless crystalline solid, soluble in

water, ethanol, ether, and chloroform

• Formation: baking, roasting, toasting, grilling, frying

• Common foods: French fries, potato chips,bread, biscuits, coffee, roasted

cereals

What is Acrylamide ?

S.N. Properties Values1. IUPAC name Prop-2 enamide2. Molecular formula C3H5NO

3. MW 71.08 g mol−1

4. Density 1.13 g/cm3

5. Melting point 84.5 °C6. Solubility in water 2.04 kg/L (at 25 °C)7. Color white crystalline solid8. Boiling point 136 °C

Properties of Acryl amide

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• 1950s: Synthetic Polyacrylamide-based flocculants

• 1960s: Synthetic coagulants in mineral processing industries

• 2002: Swedish researchers announced the discovery of acrylamide in food

Acrylamide in industrial use

6PAM

Cereals, potato & coffee : variety and growing factors

Cereals : reducing sugars are abundant → conc. Of Asparagine →AAPotato : asparagine is abundant →conc. of reducing sugar→ AA

Acrylamide production in foods

Concentrations & availability of Precursor molecules

AA Formed by Maillard reaction

between asparagine and reducing sugars

(precursors)

Factors (temp., heat intensity, water activity) in processing technologies

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Impact of Potato variety on AA Levels (Source: D. Mottram, U. Reading)

1200012800Over cooked35003500Cooked100200

Frozen frying chips

as sold

35002800Chipped & friedNd<10boiled

<30Nd<10

King Edward potatoes raw

350310Chipped & friedNd<10Boiled

<30

LC-MS-MS

Nd

GC-MS

<10

Baking potatoes raw

SNFA result (µg/kg)

Acrylamide concentration (µg/kg)

Sample

Acrylamide formation influenced by starting raw material

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Acryl amide

formation

Heat

Carbonyl source

L-Asparaginesource

• Removing or changing one of the parameter prevents formation.

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Mechanism for formation

C – CH2 – CH

NH2

COOHO

H2N

HOOH

OH

OH

OH

O

+

C – CH2 – CH

N

COOHO

H2N

Asparagine Glucose

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From Asparagine and Reducing sugar

Maillard reactionProducts

C – CH2 – CH

N

COOHO

H2N

C – CH = CH2

O

H2N

C – CH2 – CH2

N

O

H2N

- CO2

Acrylamide11

Mechanism for formation

From Asparagine and Reducing sugar

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Acrylic acidAcrolein

Mechanism for formation

From Triglycerides

Triglycerides

Heat, O2

Acrylamide

NH3

Variation in concentration of Acrylamide with temperature and time

168 170 172 174 176 178 180 182 184 1860

200

400

600

800

1000

1200

1400

2.5 min3.5 min

Temperature (0C)

Acr

ylam

ide

(ppm

)

Source: Gertz and Klosterman (2002) Eur. J. Lipid Sci. Technol. 104:762-771. 13

380 400 420 440

Temperature (Kelvin)

050

0010

000

1500

020

000

Acr

ylam

ide

(ppb

)

AA Formation as a function of Temperature

AA = 442.3 * e(0.07930*(Temp-383))

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Potato chipsFrying time: 15 minutes

Effect of pH on Acrylamide Formation

4 5 6 7 8 90

5000

10000

15000

20000

25000

30000

120 C, 40 min

150 C, 15 min

pH

AA

(pp

b)

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Effect of browning in AA formation (Source: D. Mottram, U. Reading)

1200012800Over cooked35003500Cooked100200

Frozen frying chips

as sold

35002800Chipped & friedNd<10boiled

<30Nd<10

King Edward potatoes raw

350310Chipped & friednd<10Boiled

<30

LC-MS-MS

nd

GC-MS

<10

Baking potatoes raw

SNFA result (µg/kg)

Acrylamide concentration (µg/kg)

Sample

Yield of acrylamide increases

substantially with browning

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Amount of Acrylamide in Foods (ppm)

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Category European Data FDA Data

Breads 12-3200 <10-364

Crispbread <30-1670

Crackers and Biscuits <30-2000 26-504

Cereal <30-2300 52-266

Other Grains <30

Potato Chips 150-1280 117-2762

Other Salty Snacks 122-416 12-1168

French Fries 85-1104 20-1325

Other Potato Products <20-12400Other Veg and Fruit Products 10-<50 <10-70

Amount of Acrylamide in Foods (ppm)

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Category European Data FDA Data

Meats < 30-64 < 10-116

Candy and Dessert items < 20-110 < 10-909

Cookies 36-199

Coffee and Tea 170-700 175-351

Other Nonalcoholic Beverages < 30

Alcoholic Beverages 30

Dairy Products 10-100 < 10-43

Baby Food and Formula 40-120 < 10-130

Dry Soup Mixes < 10-1184

Gravy and Seasonings 38-54

Amino Acids Level of Acrylamide Formation

Alanine <50 ppb

Asparagine 9270 ppb

Aspartic Acid <50 ppb

Cysteine <50 ppb

Glutamine 156 ppb

Lysine <50 ppb

Methionine <50 ppb

Threonine <50 ppb

Asparagine !!!

Source : Barbara Petersen, Exponent, Inc. October 2002 JIFSAN workshop19

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Food product Interval (month)

Acrylamide level (µg/kg)

Initial Second

Breakfast cereal 12 238 238

Soluble coffee powder 12 771 256

Roasted barley 9 265 225

Roasted coffee 7 203 147

Dried chicory 5 214 174

Roasted chicory 5 4015 3395

Cocoa 3 180 177

Chocolate with almond 2 94 73

Soluble chocolate powder 1 54 41

Stability of acrylamide in various foodstuffs

Adapted from Delatour et al.

Asparagine in Various Crops

• Cheese 40 – 300 mg/100gm• Asparagus 5.4 – 108 mg/100gm• Cocoa (raw) 30.9 mg/100gm - roasted @ 1250C 14.5 mg/100gm

- roasted @ 1350C 9.4 mg/100gm• Potato 500 – 1000 mg/100gm• Rye 0.2 – 2.8 mg/100gm• Wheat 0.2 – 20 mg/100gm• Corn 0.6 – 1 mg/100gm

Source: Ellin Doyle, Ph.D., Food Research Inst., U. Wisc.21

• Known neurotoxicant (IARC 2002; Manson et al. 2005)

– Peripheral neuropathy– Tingling/numbness of extremities– Loss of reflexes– Chronic CNS dysfunction and neuropathy

• Reproductive toxicity• Animal carcinogen (CNS, endocrine organs)• EPA has classified acrylamide as a B2 carcinogen

(probable human carcinogen) (IRIS2009).• Biomarker – adducts on amino acid valine of Hb.

Toxicology

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• 2 micrograms per kg body weight per day

(Office of Environmental Health Hazard Assessment)

• Exposure at a level 1,000 times greater than the MADL is expected to have no observable effect

• No Observed Adverse Effect Level (NOAEL) of 15 mg/kg bw/day were identified in mice

• Legislation under formulation

Maximum allowable dose level (MADL

• Water extraction • Analysis by GC-MS with or w/o bromination

• by LC-MS/MS • by LC-MS or -UV after deriv. with

mercaptobenzoic acid • GC-Ion Trap MS

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Acryl amide extracted with water, test portion homogenized, acidified to pH 4-5

Addition of Carrez I and Carrez II solution

Extraction with Ethylacetate hexane (80:20), Filtration over Na2SO4

Clean up with Flourisil elution of acrylamide with acetone

Evaporation, residue taken up in ethylacetate, triethylamine added

Filtration, injection into GC-MS

GC-MS method

Acrylamide Precursors – Where to Intervene

Asparagine Reducing Sugars- Glucose- Fructose- Sucrose hydrolysis?

• Factors affecting asparagine and reducing sugars- Variety of potato- Storage conditions

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Acrylamide Possible Mitigation Strategies

1. Reduction or removal of sugars. Selection of low sugar cultivar. Blanching and soaking to leach out sugars.

2. Reduction or removal of asparagines. Use of enzymes to degrade asparagine during food

processing. Blanching to leach out asparagine

3. Processing Conditions Altering time-temperature of processing. Altering heat processing methods Changing pH of food by using acids Use of antioxidants

Reduction of Acrylamide formation in Potatoes products

• Improve agronomic practices• Select potatoes variety with less asparagine• Store potatoes tubers >10°C• Blanching (82°C)• Add antioxidants• Dip slices in citric acid (0.75%) solution• Dip in NaCl, CaCl2 solution

• Use of enzyme- asparaginase• Addition of amino acids glycine.

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Reduction of Acrylamide in cereal products

• Adjustment of time and temperature during baking.

• Extend fermentation times where feasible.• Substitution of ammonium bicarbonate with

alternatives• Avoid or minimize use of reducing sugars• Avoidance of very high baking temperature• Use of asparaginase in dough to degrade

asparagine.29

Enzyme mechanism

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Impact of treating with Asparaginase

• By treating with asparaginase there was a 99% reduction in the levels of acrylamide in the potato mixture

• Product characteristics fully preserved• No change in process parameters• Commercially viable and available ???

µg/day0

5

10

15

20

25

30

Biscuit / Cookies

All Other Foods

Relative Exposure to Acrylamide in U.S. Food

French Fries & Potatoes

Breads

Potato ChipsCereal

Coffee Cakes Dried Foods Pop Corn Salty Snacks Chocolate Products Nuts/Seeds/Butters

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Conclusion

• Acrylamide formation in thermally processed foods is a major challenges for bakery, French fries and chip producing industries.

• challenges still remain in terms of the needs to develop simple and rapid test methods.

• different pre-frying treatments on the reduction of acrylamide (AA) formation are under investigation 33

What about these cereal based foods ?

34Chapati Doughnut

Selroti Puri

“Foods should not be cooked excessively...for too long or at too high a temperature... However, all food…should be cooked thoroughly to destroy food borne pathogens.”

Thanks for your kind attention

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Is it possible to cook food without forming at least some AA ?????